<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="./index.js"></script>
    <style type="text/css">
		#div1{
			height: 200px;
			width:200px;
			border:1px solid red;
		}
		#div2{
			height:100px;
			width:100px;
			border:1px solid blue;
		}
		#div3{
			height: 50px;
			width: 50px;
			border:1px solid green;
		}
	</style>
</head>
<body>
    <div id="div1">
		<div id="div2">
			<div id="div3"></div>
        </div>
        
    </div>
    <p id="demo"></p>
</body>
</html>